builtin-rerere.c

   1 #include "builtin.h"
   2 #include "cache.h"
   3 #include "path-list.h"
   4 #include "xdiff/xdiff.h"
   5 #include "xdiff-interface.h"
   6
   7 #include <time.h>
   8
   9 static const char git_rerere_usage[] =
  10 "git-rerere [clear | status | diff | gc]";
  11
  12 /* these values are days */
  13 static int cutoff_noresolve = 15;
  14 static int cutoff_resolve = 60;
  15
  16 /* if rerere_enabled == -1, fall back to detection of .git/rr-cache */
  17 static int rerere_enabled = -1;
  18
  19 static char *merge_rr_path;
  20
  21 static const char *rr_path(const char *name, const char *file)
  22 {
  23         return git_path("rr-cache/%s/%s", name, file);
  24 }
  25
  26 static time_t rerere_created_at(const char *name)
  27 {
  28         struct stat st;
  29         return stat(rr_path(name, "preimage"), &st) ? (time_t) 0 : st.st_mtime;
  30 }
  31
  32 static int has_resolution(const char *name)
  33 {
  34         struct stat st;
  35         return !stat(rr_path(name, "postimage"), &st);
  36 }
  37
  38 static void read_rr(struct path_list *rr)
  39 {
  40         unsigned char sha1[20];
  41         char buf[PATH_MAX];
  42         FILE *in = fopen(merge_rr_path, "r");
  43         if (!in)
  44                 return;
  45         while (fread(buf, 40, 1, in) == 1) {
  46                 int i;
  47                 char *name;
  48                 if (get_sha1_hex(buf, sha1))
  49                         die("corrupt MERGE_RR");
  50                 buf[40] = '\0';
  51                 name = xstrdup(buf);
  52                 if (fgetc(in) != '\t')
  53                         die("corrupt MERGE_RR");
  54                 for (i = 0; i < sizeof(buf) && (buf[i] = fgetc(in)); i++)
  55                         ; /* do nothing */
  56                 if (i == sizeof(buf))
  57                         die("filename too long");
  58                 path_list_insert(buf, rr)->util = name;
  59         }
  60         fclose(in);
  61 }
  62
  63 static struct lock_file write_lock;
  64
  65 static int write_rr(struct path_list *rr, int out_fd)
  66 {
  67         int i;
  68         for (i = 0; i < rr->nr; i++) {
  69                 const char *path;
  70                 int length;
  71                 if (!rr->items[i].util)
  72                         continue;
  73                 path = rr->items[i].path;
  74                 length = strlen(path) + 1;
  75                 if (write_in_full(out_fd, rr->items[i].util, 40) != 40 ||
  76                     write_in_full(out_fd, "\t", 1) != 1 ||
  77                     write_in_full(out_fd, path, length) != length)
  78                         die("unable to write rerere record");
  79         }
  80         if (commit_lock_file(&write_lock) != 0)
  81                 die("unable to write rerere record");
  82         return 0;
  83 }
  84
  85 static int handle_file(const char *path,
  86          unsigned char *sha1, const char *output)
  87 {
  88         SHA_CTX ctx;
  89         char buf[1024];
  90         int hunk = 0, hunk_no = 0;
  91         struct strbuf one, two;
  92         FILE *f = fopen(path, "r");
  93         FILE *out = NULL;
  94
  95         if (!f)
  96                 return error("Could not open %s", path);
  97
  98         if (output) {
  99                 out = fopen(output, "w");
 100                 if (!out) {
 101                         fclose(f);
 102                         return error("Could not write %s", output);
 103                 }
 104         }
 105
 106         if (sha1)
 107                 SHA1_Init(&ctx);
 108
 109         strbuf_init(&one, 0);
 110         strbuf_init(&two,  0);
 111         while (fgets(buf, sizeof(buf), f)) {
 112                 if (!prefixcmp(buf, "<<<<<<< "))
 113                         hunk = 1;
 114                 else if (!prefixcmp(buf, "======="))
 115                         hunk = 2;
 116                 else if (!prefixcmp(buf, ">>>>>>> ")) {
 117                         if (strbuf_cmp(&one, &two) > 0)
 118                                 strbuf_swap(&one, &two);
 119                         hunk_no++;
 120                         hunk = 0;
 121                         if (out) {
 122                                 fputs("<<<<<<<\n", out);
 123                                 fwrite(one.buf, one.len, 1, out);
 124                                 fputs("=======\n", out);
 125                                 fwrite(two.buf, two.len, 1, out);
 126                                 fputs(">>>>>>>\n", out);
 127                         }
 128                         if (sha1) {
 129                                 SHA1_Update(&ctx, one.buf ? one.buf : "",
 130                                             one.len + 1);
 131                                 SHA1_Update(&ctx, two.buf ? two.buf : "",
 132                                             two.len + 1);
 133                         }
 134                         strbuf_reset(&one);
 135                         strbuf_reset(&two);
 136                 } else if (hunk == 1)
 137                         strbuf_addstr(&one, buf);
 138                 else if (hunk == 2)
 139                         strbuf_addstr(&two, buf);
 140                 else if (out)
 141                         fputs(buf, out);
 142         }
 143         strbuf_release(&one);
 144         strbuf_release(&two);
 145
 146         fclose(f);
 147         if (out)
 148                 fclose(out);
 149         if (sha1)
 150                 SHA1_Final(sha1, &ctx);
 151         if (hunk) {
 152                 if (output)
 153                         unlink(output);
 154                 return error("Could not parse conflict hunks in %s", path);
 155         }
 156         return hunk_no;
 157 }
 158
 159 static int find_conflict(struct path_list *conflict)
 160 {
 161         int i;
 162         if (read_cache() < 0)
 163                 return error("Could not read index");
 164         for (i = 0; i+1 < active_nr; i++) {
 165                 struct cache_entry *e2 = active_cache[i];
 166                 struct cache_entry *e3 = active_cache[i+1];
 167                 if (ce_stage(e2) == 2 &&
 168                     ce_stage(e3) == 3 &&
 169                     ce_same_name(e2, e3) &&
 170                     S_ISREG(e2->ce_mode) &&
 171                     S_ISREG(e3->ce_mode)) {
 172                         path_list_insert((const char *)e2->name, conflict);
 173                         i++; /* skip over both #2 and #3 */
 174                 }
 175         }
 176         return 0;
 177 }
 178
 179 static int merge(const char *name, const char *path)
 180 {
 181         int ret;
 182         mmfile_t cur, base, other;
 183         mmbuffer_t result = {NULL, 0};
 184         xpparam_t xpp = {XDF_NEED_MINIMAL};
 185
 186         if (handle_file(path, NULL, rr_path(name, "thisimage")) < 0)
 187                 return 1;
 188
 189         if (read_mmfile(&cur, rr_path(name, "thisimage")) ||
 190                         read_mmfile(&base, rr_path(name, "preimage")) ||
 191                         read_mmfile(&other, rr_path(name, "postimage")))
 192                 return 1;
 193         ret = xdl_merge(&base, &cur, "", &other, "",
 194                         &xpp, XDL_MERGE_ZEALOUS, &result);
 195         if (!ret) {
 196                 FILE *f = fopen(path, "w");
 197                 if (!f)
 198                         return error("Could not write to %s", path);
 199                 fwrite(result.ptr, result.size, 1, f);
 200                 fclose(f);
 201         }
 202
 203         free(cur.ptr);
 204         free(base.ptr);
 205         free(other.ptr);
 206         free(result.ptr);
 207
 208         return ret;
 209 }
 210
 211 static void unlink_rr_item(const char *name)
 212 {
 213         unlink(rr_path(name, "thisimage"));
 214         unlink(rr_path(name, "preimage"));
 215         unlink(rr_path(name, "postimage"));
 216         rmdir(git_path("rr-cache/%s", name));
 217 }
 218
 219 static void garbage_collect(struct path_list *rr)
 220 {
 221         struct path_list to_remove = { NULL, 0, 0, 1 };
 222         DIR *dir;
 223         struct dirent *e;
 224         int i, cutoff;
 225         time_t now = time(NULL), then;
 226
 227         dir = opendir(git_path("rr-cache"));
 228         while ((e = readdir(dir))) {
 229                 const char *name = e->d_name;
 230                 if (name[0] == '.' &&
 231                     (name[1] == '\0' || (name[1] == '.' && name[2] == '\0')))
 232                         continue;
 233                 then = rerere_created_at(name);
 234                 if (!then)
 235                         continue;
 236                 cutoff = (has_resolution(name)
 237                           ? cutoff_resolve : cutoff_noresolve);
 238                 if (then < now - cutoff * 86400)
 239                         path_list_append(name, &to_remove);
 240         }
 241         for (i = 0; i < to_remove.nr; i++)
 242                 unlink_rr_item(to_remove.items[i].path);
 243         path_list_clear(&to_remove, 0);
 244 }
 245
 246 static int outf(void *dummy, mmbuffer_t *ptr, int nbuf)
 247 {
 248         int i;
 249         for (i = 0; i < nbuf; i++)
 250                 if (write_in_full(1, ptr[i].ptr, ptr[i].size) != ptr[i].size)
 251                         return -1;
 252         return 0;
 253 }
 254
 255 static int diff_two(const char *file1, const char *label1,
 256                 const char *file2, const char *label2)
 257 {
 258         xpparam_t xpp;
 259         xdemitconf_t xecfg;
 260         xdemitcb_t ecb;
 261         mmfile_t minus, plus;
 262
 263         if (read_mmfile(&minus, file1) || read_mmfile(&plus, file2))
 264                 return 1;
 265
 266         printf("--- a/%s\n+++ b/%s\n", label1, label2);
 267         fflush(stdout);
 268         xpp.flags = XDF_NEED_MINIMAL;
 269         memset(&xecfg, 0, sizeof(xecfg));
 270         xecfg.ctxlen = 3;
 271         ecb.outf = outf;
 272         xdi_diff(&minus, &plus, &xpp, &xecfg, &ecb);
 273
 274         free(minus.ptr);
 275         free(plus.ptr);
 276         return 0;
 277 }
 278
 279 static int do_plain_rerere(struct path_list *rr, int fd)
 280 {
 281         struct path_list conflict = { NULL, 0, 0, 1 };
 282         int i;
 283
 284         find_conflict(&conflict);
 285
 286         /*
 287          * MERGE_RR records paths with conflicts immediately after merge
 288          * failed.  Some of the conflicted paths might have been hand resolved
 289          * in the working tree since then, but the initial run would catch all
 290          * and register their preimages.
 291          */
 292
 293         for (i = 0; i < conflict.nr; i++) {
 294                 const char *path = conflict.items[i].path;
 295                 if (!path_list_has_path(rr, path)) {
 296                         unsigned char sha1[20];
 297                         char *hex;
 298                         int ret;
 299                         ret = handle_file(path, sha1, NULL);
 300                         if (ret < 1)
 301                                 continue;
 302                         hex = xstrdup(sha1_to_hex(sha1));
 303                         path_list_insert(path, rr)->util = hex;
 304                         if (mkdir(git_path("rr-cache/%s", hex), 0755))
 305                                 continue;;
 306                         handle_file(path, NULL, rr_path(hex, "preimage"));
 307                         fprintf(stderr, "Recorded preimage for '%s'\n", path);
 308                 }
 309         }
 310
 311         /*
 312          * Now some of the paths that had conflicts earlier might have been
 313          * hand resolved.  Others may be similar to a conflict already that
 314          * was resolved before.
 315          */
 316
 317         for (i = 0; i < rr->nr; i++) {
 318                 int ret;
 319                 const char *path = rr->items[i].path;
 320                 const char *name = (const char *)rr->items[i].util;
 321
 322                 if (has_resolution(name)) {
 323                         if (!merge(name, path)) {
 324                                 fprintf(stderr, "Resolved '%s' using "
 325                                                 "previous resolution.\n", path);
 326                                 goto mark_resolved;
 327                         }
 328                 }
 329
 330                 /* Let's see if we have resolved it. */
 331                 ret = handle_file(path, NULL, NULL);
 332                 if (ret)
 333                         continue;
 334
 335                 fprintf(stderr, "Recorded resolution for '%s'.\n", path);
 336                 copy_file(rr_path(name, "postimage"), path, 0666);
 337         mark_resolved:
 338                 rr->items[i].util = NULL;
 339         }
 340
 341         return write_rr(rr, fd);
 342 }
 343
 344 static int git_rerere_config(const char *var, const char *value, void *cb)
 345 {
 346         if (!strcmp(var, "gc.rerereresolved"))
 347                 cutoff_resolve = git_config_int(var, value);
 348         else if (!strcmp(var, "gc.rerereunresolved"))
 349                 cutoff_noresolve = git_config_int(var, value);
 350         else if (!strcmp(var, "rerere.enabled"))
 351                 rerere_enabled = git_config_bool(var, value);
 352         else
 353                 return git_default_config(var, value, cb);
 354         return 0;
 355 }
 356
 357 static int is_rerere_enabled(void)
 358 {
 359         struct stat st;
 360         const char *rr_cache;
 361         int rr_cache_exists;
 362
 363         if (!rerere_enabled)
 364                 return 0;
 365
 366         rr_cache = git_path("rr-cache");
 367         rr_cache_exists = !stat(rr_cache, &st) && S_ISDIR(st.st_mode);
 368         if (rerere_enabled < 0)
 369                 return rr_cache_exists;
 370
 371         if (!rr_cache_exists &&
 372             (mkdir(rr_cache, 0777) || adjust_shared_perm(rr_cache)))
 373                 die("Could not create directory %s", rr_cache);
 374         return 1;
 375 }
 376
 377 static int setup_rerere(struct path_list *merge_rr)
 378 {
 379         int fd;
 380
 381         git_config(git_rerere_config, NULL);
 382         if (!is_rerere_enabled())
 383                 return -1;
 384
 385         merge_rr_path = xstrdup(git_path("rr-cache/MERGE_RR"));
 386         fd = hold_lock_file_for_update(&write_lock, merge_rr_path, 1);
 387         read_rr(merge_rr);
 388         return fd;
 389 }
 390
 391 int rerere(void)
 392 {
 393         struct path_list merge_rr = { NULL, 0, 0, 1 };
 394         int fd;
 395
 396         fd = setup_rerere(&merge_rr);
 397         if (fd < 0)
 398                 return 0;
 399         return do_plain_rerere(&merge_rr, fd);
 400 }
 401
 402 int cmd_rerere(int argc, const char **argv, const char *prefix)
 403 {
 404         struct path_list merge_rr = { NULL, 0, 0, 1 };
 405         int i, fd;
 406
 407         fd = setup_rerere(&merge_rr);
 408         if (fd < 0)
 409                 return 0;
 410
 411         if (argc < 2)
 412                 return do_plain_rerere(&merge_rr, fd);
 413         else if (!strcmp(argv[1], "clear")) {
 414                 for (i = 0; i < merge_rr.nr; i++) {
 415                         const char *name = (const char *)merge_rr.items[i].util;
 416                         if (!has_resolution(name))
 417                                 unlink_rr_item(name);
 418                 }
 419                 unlink(merge_rr_path);
 420         } else if (!strcmp(argv[1], "gc"))
 421                 garbage_collect(&merge_rr);
 422         else if (!strcmp(argv[1], "status"))
 423                 for (i = 0; i < merge_rr.nr; i++)
 424                         printf("%s\n", merge_rr.items[i].path);
 425         else if (!strcmp(argv[1], "diff"))
 426                 for (i = 0; i < merge_rr.nr; i++) {
 427                         const char *path = merge_rr.items[i].path;
 428                         const char *name = (const char *)merge_rr.items[i].util;
 429                         diff_two(rr_path(name, "preimage"), path, path, path);
 430                 }
 431         else
 432                 usage(git_rerere_usage);
 433
 434         path_list_clear(&merge_rr, 1);
 435         return 0;
 436 }